Araldite's great stuff for bonding thermosetting plastics, but the plasticiser used in some (most?) thermo plastics can compromise the bond.

Jim

I hate it when some home repairer uses epoxy resin to glue in a violin neck. At least it softens with heat (hairdryer) & I can remove it, but I doubt that sort of heat would soften the glue enough in that situation though, although as it warms enough it can 'creep'.

I hate it when some home repairer uses epoxy resin to glue in a violin neck. At least it softens with heat (hairdryer) & I can remove it, but I doubt that sort of heat would soften the glue enough in that situation though, although as it warms enough it can 'creep'.

Not sure what you're saying here, Ross. When an epoxy resin adhesive like Araldite sets, it won't soften with heat. The setting is an irreversible chemical process. I thought animal glue was still used in violins, which softens with heat and facilitates repair of the instrument.

Not sure what you're saying here, Ross. When an epoxy resin adhesive like Araldite sets, it won't soften with heat. The setting is an irreversible chemical process. I thought animal glue was still used in violins, which softens with heat and facilitates repair of the instrument.

Jim

Sorry Jim, but that is totally incorrect information.

Araldite remains stable in temperatures up to boiling point but higher temps soften it. Hence it is useless on anything that has a high temp such as ovens, engines, electric heating elements etc. I seem to remember the melting, softening point is 200 degrees centigrade. It will possibly harden again upon cooling but the bond will probably have been compromised.

"Araldite" however is merely a brand name producing numerous epoxy resin glues. There is a high temp variant available but not usually found in DIY outlets.

I seem to remember the melting, softening point is 200 degrees centigrade. It will possibly harden again upon cooling but the bond will probably have been compromised.

I don't think it melts so much as degrades and breaks down, and on cooling its original properties won't be restored. Epoxy resins are thermosetting resins - they set with heat undergoing an irreversible catalytic process, although the heat can be moderate even room temperature. If I've got an item that I want to bond and it will stand low heat (say 100 C) I'll put it in a cool oven. The nice thing about using moderate heat is that the mixed resin will flow into irregularities and interstices ensuring a good bond. Also any air bubbles are dissipated.

Not sure what you're saying here, Ross. When an epoxy resin adhesive like Araldite sets, it won't soften with heat. The setting is an irreversible chemical process. I thought animal glue was still used in violins, which softens with heat and facilitates repair of the instrument.

Jim

If you have anything with it spilt on, try a hair dryer on it & notice how it softens (with a knife or other sharp implement), but maybe it has been 5 minute Araldite. I can pick it off as it does, thankfully. Yes, animal glue (Russian Hide Glue) should be used, but sometimes some people have a go at doing their own repairs & later bring it to be done properly. Then it costs more as I have to undo what they've done. As I mentioned earlier, if a neck had been reglued in with Araldite then heating with a hair dryer I can eventually remove it as it softens. If it's hide glue, then after loosening the edges with a knife the neck then has to be cracked out, since the hide glue goes brittle.

If you have anything with it spilt on, try a hair dryer on it & notice how it softens (with a knife or other sharp implement), but maybe it has been 5 minute Araldite. I can pick it off as it does, thankfully. Yes, animal glue (Russian Hide Glue) should be used, but sometimes some people have a go at doing their own repairs & later bring it to be done properly. Then it costs more as I have to undo what they've done. As I mentioned earlier, if a neck had been reglued in with Araldite then heating with a hair dryer I can eventually remove it as it softens. If it's hide glue, then after loosening the edges with a knife the neck then has to be cracked out, since the hide glue goes brittle.

Is it possible that the amateur epoxy repair was done without removing the remains of the animal glue (I'd bet it was)? In this case it was probably the animal glue underneath that was softening, enabling the removal of the epoxy.

5 min epoxy is pretty inferior to the 14 hr stuff. 5 min epoxy never seems to set 'glass hard' like the longer curing time types.

I've used 'J B Weld' epoxy for building camping stoves. It will stand up to 290 C.